Once Weekly Fish Consumption Linked to Reduced Cognitive Decline

Fish consumption, about one serving per week or more, is associated with reduced cognitive decline, according to the results of a prospective cohort study. "Dietary intake of fish and the omega-3 fatty acids have been associated with lower risk of Alzheimer disease and stroke," write Martha Clare Morris, ScD, from Rush University Medical Center in Chicago, Illinois, and colleagues. "Dietary intakes of the omega-3 fatty acids, and especially docosahexaenoic acid (DHA), are essential for neurocognitive development and normal brain functioning."

The Chicago Health and Aging Project followed up residents of a Chicago community who were 65 years and older. The primary outcome was change in a global cognitive score estimated from mixed models and computed by summing scores of four standardized tests. Participants had in-home cognitive assessments three times during six years of follow-up.

Average rate of decline in cognitive scores was 0.04 standardized units per year (SU/year). In mixed models adjusted for age, sex, race, education, cognitive activity, physical activity, alcohol consumption, and total energy intake, fish consumption was associated with a slower rate of cognitive decline. Compared with a rate of decline of -0.100 SU per year for persons who consumed fish less than weekly, the rate was 10% slower (-0.090 SU/year) for persons who consumed one fish meal per week and 13% slower (-0.088 SU/year) for persons who consumed at least two fish meals per week.

Cardiovascular-related conditions or fruit and vegetable intake did not affect the association between fish consumption and slower cognitive decline. However, the association was modified after adjustment for intakes of saturated, polyunsaturated, and trans fats. There was little evidence that omega-3 polyunsaturated fatty acid intake was associated with cognitive change. "Fish consumption may be associated with slower cognitive decline with age," the authors write.

"This study suggests that eating one or more fish meals per week may protect against cognitive decline associated with older age," the authors conclude. "More precise studies of the different dietary constituents of fish should help to understand the nature of the association."

Practice Pearls · Eating fish once per week can reduce the risk of Alzheimer’s disease, and this effect is probably mediated through higher intake of omega-3 polyunsaturated fatty acids and DHA. · Fish consumption at least once per week can slow the rate of cognitive decline in older adults. This effect is attenuated somewhat when adjusting for fat intake.

Arch Neurol. Posted online Oct. 10, 2005.

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